Since July 1, 1973, we are one of five centers participating in a randomized clinical trial of 5-fluorouracil (5FU) and cyclophosphamide (cytoxan) and standard therapy in patients with advanced, endocrine- resistant prostatic cancer. According to the protocol designed by the Working Cadre of the National Prostatic Cancer Project (NPCP), patients are randomly assigned to receive: (1) 5FU, 600 mg per M2 body surface I.V. each week, or (2) cytoxan, 1000 mg per M2 body surface area I.V. every three weeks, or (3) standard therapy which includes all non- chemotherapeutic modalities. Patients are monitored with weekly hemograms, serum chemistries, and plasma acid phosphatase determinations. Also, excretory urograms, chest x-rays and skeletal survey are obtained at six-week intervals. Patients manifesting evidence of objective tumor progression after 12 weeks treatment with one of the chemotherapeutic agents are "crossed over" to the other agent. As of February 28, 1974, we have entered nine patients into this study of a total of 49 patients from all centers, the goal being 30 from each center or a total of 150. Data are being analyzed periodically by the Central Statistical Office of the National Prostatic Cancer Project in Buffalo and will be the subject of a joint report in June, 1974.